Re: [Netconf] [Technical Errata Reported] RFC8040 (5565)

Martin Bjorklund <mbj@tail-f.com> Mon, 03 December 2018 09:48 UTC

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Subject: Re: [Netconf] [Technical Errata Reported] RFC8040 (5565)
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Qin Wu <bill.wu@huawei.com> wrote:
> See data-missing definition in RFC6241:
> "
>    error-tag:      data-missing
>    error-type:     application
>    error-severity: error
>    error-info:     none
>    Description:    Request could not be completed because the relevant
>                    data model content does not exist.  For example,
>                    a "delete" operation was attempted on
>                    data that does not exist.
> 
> "
> And status code 409 definition in RFC7231
> "
> 6.5.8.  409 Conflict
> 
>    The 409 (Conflict) status code indicates that the request could not
>    be completed due to a conflict with the current state of the target
>    resource.  This code is used in situations where the user might be
>    able to resolve the conflict and resubmit the request.  The server
>    SHOULD generate a payload that includes enough information for a user
>    to recognize the source of the conflict.
> 
> 6.5.4.  404 Not Found
> 
>    The 404 (Not Found) status code indicates that the origin server did
>    not find a current representation for the target resource or is not
>    willing to disclose that one exists.  A 404 status code does not
>    indicate whether this lack of representation is temporary or
>    permanent; the 410 (Gone) status code is preferred over 404 if the
>    origin server knows, presumably through some configurable means, that
>    the condition is likely to be permanent.
> 
> "
> Which make me feel data missing is more related to 404 instead of 409. Wrong?

404 means that *the requested resource* doesn't exist.

The example "delete" operation in 6241 refers to an edit-config with
operation "delete".  The corresponding RESTCONF operation is "delete"
within a YANG PATCH.  In this case, the requested resource exists, so
a 404 would not be correct.

So there are certainly cases where "data-missing" does not mean 404.

But I guess there are also cases where "data-missing" will actually
correspond to a 404.  For example an edit-config that just tries to
delete a non-existing node will be a "data-missing", and if the
corresponding RESTCONF request is a DELETE on the resource, it will be
404 - but if the corresponding RESTCONF request is a YANG PATCH with a
"delete" edit, it will be 409.

So, maybe the proper fix is

               | data-missing            | 404, 409           |



/martin



> 
> -Qin
> -----邮件原件-----
> 发件人: Martin Bjorklund [mailto:mbj@tail-f.com] 
> 发送时间: 2018年12月3日 16:54
> 收件人: rfc-editor@rfc-editor.org
> 抄送: andy@yumaworks.com; kwatsen@juniper.net; ibagdona@gmail.com; warren@kumari.net; mjethanandani@gmail.com; Qin Wu; netconf@ietf.org
> 主题: Re: [Technical Errata Reported] RFC8040 (5565)
> 
> Hi,
> 
> I don't think this errata should be accepted.  404 means that the requested resource doesn't exist, but "data-missing" can be returned e.g. if you try to patch an existing resource of type leafref to point to a non-existing leaf.
> 
> 
> /martin
> 
> 
> RFC Errata System <rfc-editor@rfc-editor.org> wrote:
> > The following errata report has been submitted for RFC8040, "RESTCONF 
> > Protocol".
> > 
> > --------------------------------------
> > You may review the report below and at:
> > http://www.rfc-editor.org/errata/eid5565
> > 
> > --------------------------------------
> > Type: Technical
> > Reported by: Qin Wu <bill.wu@huawei.com>
> > 
> > Section: 7
> > 
> > Original Text
> > -------------
> >               +-------------------------+------------------+
> >               | error-tag               | status code      |
> >               +-------------------------+------------------+
> >               | in-use                  | 409              |
> >               | lock-denied             | 409              |
> >               | resource-denied         | 409              |
> >               | data-exists             | 409              |
> >               | data-missing            | 409              |
> > 
> > 
> > Corrected Text
> > --------------
> >               +-------------------------+------------------+
> >               | error-tag               | status code      |
> >               +-------------------------+------------------+
> >               | in-use                  | 409              |
> >               | lock-denied             | 409              |
> >               | resource-denied         | 409              |
> >               | data-exists             | 409              |
> >               | data-missing            | 404              |
> > 
> > 
> > Notes
> > -----
> > The <error-tag> data missing should be mapped to status code '404' instead of '409' to get consistent with the defintion of data-missing in RFC6241.
> > 
> > Instructions:
> > -------------
> > This erratum is currently posted as "Reported". If necessary, please 
> > use "Reply All" to discuss whether it should be verified or rejected. 
> > When a decision is reached, the verifying party can log in to change 
> > the status and edit the report, if necessary.
> > 
> > --------------------------------------
> > RFC8040 (draft-ietf-netconf-restconf-18)
> > --------------------------------------
> > Title               : RESTCONF Protocol
> > Publication Date    : January 2017
> > Author(s)           : A. Bierman, M. Bjorklund, K. Watsen
> > Category            : PROPOSED STANDARD
> > Source              : Network Configuration
> > Area                : Operations and Management
> > Stream              : IETF
> > Verifying Party     : IESG
> >